The findings are clear and far from surprising: sitting in front of a television screen for hours on end has negative effects on health. But this latest study shows that the curve could be reversed if an hour spent watching TV were replaced by physical activity.
“For each increase of two hours per day in time spent watching television, there was a 12% decrease in odds of healthy ageing,” researchers outlined.
The study, spanning 20 years, involved over 45,000 women from the Nurses’ Health Study, aged at least 50 and not suffering from any chronic disease at the start of the study in 1992.
The lifestyle habits of these participants were tracked, including time spent sitting at work and at home, time spent watching TV, and hours spent standing or walking around at home. This data was then compared with information on their health and ageing over time.
Among the negative consequences, the study warns that excess sitting can affect not only skeletal muscles but also chronic diseases by “reducing insulin sensitivity, disrupting postprandial glucose and lipid metabolism, and increasing inflammation”.
Prolonged sitting “may negatively impact the peripheral and central vascular markers, such as the cerebral blood flow, which may explain the negative association of television watching and different domains of healthy ageing in this study”, the researchers noted.
If watching TV is the enemy of good health, then exercise – even gentle exercise – can be an ally. According to the experts, switching an hour of TV for an hour of light physical activity can increase your chances of reaching age 70 in good physical and mental health by 8%.
Opting for a more intense one-hour workout can significantly tip the balance in your favour, with a 28% chance of maintaining good health.
For the less energetic, the researchers even suggest that sleeping is preferable to watching TV: “Replacing television watching with moderate-to-vigorous physical activity or even light physical activity, or sleep (in participants who sleep seven or less hours per day) was all associated with improved healthy aging,” they concluded.
Bad habits while watching TV
If the experts consider watching TV to be a particularly unhealthy activity, this is not only because of the lack of movement involved, but also due to the harmful habits that often accompany it. For example, watching TV is often associated with an unhealthy diet and a higher calorie intake.
“Participants with longer television watching time were older, less educated, more likely to smoke or drink alcohol, more likely to have hypertension and high cholesterol, and more likely to have higher BMI and calorie intake and lower diet quality compared with those who spent less time watching television,” the researchers observed.
“Also, studies have reported that individuals who spend more time watching television tend to follow unhealthy eating patterns and increase total energy intake.”
This finding is all the more worrying given that 84% of older adults in the US spend two hours or more a day sitting and watching TV. Just over a quarter (25.7%) say they sit for more than eight hours a day, and 44.6% say they are inactive, the study added.